In recent years, in a power tool for rotating and driving a tip end tool such as a drill or a driver by using a motor to perform a required operation, a brushless motor has been employed. The brushless motor is a DC motor having no brush (rectifying brush), for example, and employs coils (windings) on a stator side and a permanent magnet on a rotor side, whereby a power driven by an inverter is sequentially supplied to the predetermined coils to rotate the rotor. In the brushless motor, switching elements for selectively supplying the currents to the coils wound around the stator are disposed on a circuit board located near the motor. In JP-2004-357371-A, for example, switching elements are disposed on a circuit board of an almost circular shape attached to the rear side (a side in opposite to the tip end tool side) of a motor.
Conventionally, in a method of mounting switching elements on the rear side of a circuit board, the switching elements are disposed so that the height direction of the switching elements is in parallel to the rotation shaft of the motor in view of the cooling and the mounting space. However, according to such the arrangement, although the good performance can be realized in view of the cooling, it is required to provide a space corresponding to the height of the circuit board and the switching elements on the rear side in the axial direction of the motor. Further, conventionally, the switching elements are fixed on the board so that through holes are formed at the circuit board, then leg portions of the switching elements are passed through the through holes and the leg portions are fixed by the soldering from the rear side thereof. Thus, in the power tool shown in JP-2004-357371-A, since the switching elements are provided so that the longitudinal direction thereof becomes almost orthogonal to the circuit board, the length of a housing in its longitudinal direction becomes long when the brushless motor is applied to the power tool.
On the other hand, it is considered to provide the circuit board at another position in place of the rear side of the motor in order to avoid that the length of the housing in its longitudinal direction becomes long. However, in this case, a wiring for coupling the coils of the motor with the switching elements becomes long and further it is difficult to dispose the board at another position in view of heat dissipation of the switching elements which likely generate heat.